Combine the first 13 ingredients (through the salt). Add the ground beef and mix well, using your hands. Shape the meat into six individual loaves. Freeze until partially frozen, approximately 30 minutes.
Preheat a barbecue grill to medium.
Spray a grill basket or grill pan with cooking spray. Place each loaf into the grill basket and sear over indirect heat for 10 minutes. Flip each loaf and sear the other side for another 10 minutes. Flip once more and close the lid. Cook for another 10 minutes, or until the meat is no longer pink, and a meat thermometer inserted into one of the loaves reads 160°F. Brush each loaf with ketchup, if desired. Let stand for 10 minutes before slicing.